Abstract: In this invention truth logic is defined as that “Light existence=TRUE” and “NO light or Dark=FALSE”. And through the optical principles (: “Fraunhofer” single slit & “Young” double slits light diffraction pattern), I have designed logical function gates (AND, OR, XOR & NOT), using the optical equipments and a coherent light beam (Laser beam), with no interference of any electronic circuits or devices. This design would lead us to make Optological Gates which run at the light speed, so we would have logical function gates with very high speed.